Codebase Analyzer

Expert skill for comprehensive codebase analysis and quality assessment. Specializes in pattern detection, code duplication analysis, performance optimization, dependency auditing, and automated code review.

Core Capabilities

1. Pattern Detection

• Design patterns (Singleton, Factory, Observer, etc.)
• React patterns (HOC, Render Props, Hooks, Compound Components)
• Anti-patterns (God components, Prop drilling, Premature optimization)
• Architectural patterns (MVC, MVVM, Flux, Clean Architecture)
• Code smells (Long methods, large classes, duplicated code)

2. Code Duplication Analysis

• Exact code duplication
• Similar code blocks (clone detection)
• Copy-paste programming detection
• Opportunities for abstraction
• Refactoring suggestions
• DRY (Don't Repeat Yourself) violations

3. Optimization Opportunities

• Performance bottlenecks
• Unnecessary re-renders (React)
• Bundle size optimization
• Memory leaks
• Inefficient algorithms
• Database query optimization
• Network request optimization

4. Dependency Analysis

• Unused dependencies
• Outdated packages
• Security vulnerabilities
• Circular dependencies
• Dependency graph visualization
• Import/export analysis
• Package size impact

5. Code Quality Metrics

• Cyclomatic complexity
• Code coverage
• Maintainability index
• Technical debt assessment
• Lines of code (LOC)
• Comment ratio
• Test-to-code ratio

6. Automated Code Review

• Style consistency
• Best practices adherence
• Accessibility issues
• Type safety problems
• Security vulnerabilities
• Performance concerns
• Documentation quality

Workflow

Phase 1: Initial Analysis

1. Codebase Discovery

   • Scan directory structure
   • Identify project type (React, Vue, Node.js, etc.)
   • Detect frameworks and libraries
   • Map file organization

2. Metric Collection

   • Count files, lines, components
   • Measure code complexity
   • Check test coverage
   • Analyze bundle size

3. Quick Health Check

   • TypeScript errors
   • Linting issues
   • Test failures
   • Build warnings

Phase 2: Deep Analysis

1. Pattern Detection

   • Identify common patterns
   • Detect anti-patterns
   • Find inconsistencies
   • Note architectural issues

2. Duplication Analysis

   • Find duplicate code
   • Identify similar structures
   • Suggest abstractions
   • Calculate duplication percentage

3. Dependency Audit

   • Check for vulnerabilities
   • Find unused dependencies
   • Identify outdated packages
   • Analyze bundle impact

4. Performance Analysis

   • Identify bottlenecks
   • Find unnecessary renders
   • Check bundle sizes
   • Analyze load times

Phase 3: Reporting & Recommendations

1. Generate Report

   • Executive summary
   • Detailed findings
   • Metrics and charts
   • Priority rankings

2. Provide Recommendations

   • Quick wins
   • High-impact improvements
   • Long-term refactoring
   • Best practices

3. Create Action Plan

   • Prioritized tasks
   • Effort estimates
   • Implementation guides
   • Success metrics

Analysis Techniques

Pattern Detection Scripts

Find Large Components

// analyze-components.ts
import { readFileSync, readdirSync, statSync } from 'fs'
import { join } from 'path'

interface ComponentMetrics {
  file: string
  lines: number
  complexity: number
  hooks: number
  props: number
}

function analyzeComponent(filePath: string): ComponentMetrics {
  const content = readFileSync(filePath, 'utf-8')
  const lines = content.split('\n').length

  // Count hooks
  const hookMatches = content.match(/use[A-Z]\w+/g) || []
  const hooks = new Set(hookMatches).size

  // Estimate complexity (simplified)
  const complexity =
    (content.match(/if|else|switch|case|for|while|&&|\|\|/g) || []).length

  // Count props
  const propsMatch = content.match(/interface \w+Props \{([^}]+)\}/)
  const props = propsMatch
    ? propsMatch[1].split('\n').filter(l => l.trim()).length
    : 0

  return { file: filePath, lines, complexity, hooks, props }
}

function findLargeComponents(dir: string): ComponentMetrics[] {
  const results: ComponentMetrics[] = []

  function walk(currentDir: string) {
    const files = readdirSync(currentDir)

    for (const file of files) {
      const filePath = join(currentDir, file)
      const stat = statSync(filePath)

      if (stat.isDirectory()) {
        if (!file.includes('node_modules') && !file.includes('dist')) {
          walk(filePath)
        }
      } else if (file.match(/\.(tsx|jsx)$/)) {
        const metrics = analyzeComponent(filePath)
        if (metrics.lines > 200 || metrics.complexity > 20) {
          results.push(metrics)
        }
      }
    }
  }

  walk(dir)
  return results.sort((a, b) => b.lines - a.lines)
}

// Usage
const largeComponents = findLargeComponents('./src')
console.table(largeComponents)

Detect Code Duplication

# Using jscpd (JavaScript Copy/Paste Detector)
npx jscpd src/ --min-lines 5 --min-tokens 50 --format markdown -o duplication-report.md

// .jscpd.json
{
  "threshold": 3,
  "reporters": ["html", "markdown", "console"],
  "ignore": [
    "**/node_modules/**",
    "**/dist/**",
    "**/*.test.ts",
    "**/*.test.tsx"
  ],
  "format": ["typescript", "javascript", "jsx", "tsx"],
  "minLines": 5,
  "minTokens": 50
}

Find Unused Exports

# Using ts-prune
npx ts-prune --error

# Using depcheck for unused dependencies
npx depcheck

Analyze Bundle Size

# Using webpack-bundle-analyzer
npm run build -- --analyze

# Using source-map-explorer
npx source-map-explorer 'dist/**/*.js'

Complexity Analysis

Cyclomatic Complexity

# Using complexity-report
npx complexity-report src/ --format json -o complexity.json

// analyze-complexity.ts
import { ESLint } from 'eslint'

async function analyzeComplexity() {
  const eslint = new ESLint({
    overrideConfig: {
      rules: {
        'complexity': ['error', { max: 10 }],
        'max-lines-per-function': ['error', { max: 50 }],
        'max-depth': ['error', { max: 4 }],
        'max-params': ['error', { max: 4 }],
      },
    },
  })

  const results = await eslint.lintFiles(['src/**/*.{ts,tsx}'])
  const highComplexity = results
    .filter(r => r.messages.some(m => m.ruleId === 'complexity'))

  return highComplexity
}

Dependency Analysis

Security Audit

# npm audit
npm audit --json > audit-report.json

# Fix automatically
npm audit fix

# Snyk security scan
npx snyk test

# Check for vulnerabilities with detailed report
npm audit --audit-level=moderate

Unused Dependencies

# depcheck
npx depcheck --json > unused-deps.json

# unimported - find unused files
npx unimported

# List globally installed but unused
npm list -g --depth=0

Outdated Packages

# Check outdated packages
npm outdated

# Interactive update
npx npm-check-updates -i

# Update all to latest
npx npm-check-updates -u && npm install

Analyze Import Costs

// Using import-cost analysis
// Shows package sizes in IDE

// Check bundle impact
import { visualizer } from 'rollup-plugin-visualizer'

// In rollup/vite config
plugins: [
  visualizer({
    filename: './dist/stats.html',
    open: true,
    gzipSize: true,
    brotliSize: true,
  }),
]

Performance Analysis

React Performance

// find-render-issues.ts
import { readFileSync } from 'fs'
import { glob } from 'glob'

interface RenderIssue {
  file: string
  issue: string
  line: number
}

function findRenderIssues(): RenderIssue[] {
  const issues: RenderIssue[] = []
  const files = glob.sync('src/**/*.{tsx,jsx}')

  for (const file of files) {
    const content = readFileSync(file, 'utf-8')
    const lines = content.split('\n')

    lines.forEach((line, idx) => {
      // Find inline function declarations in JSX
      if (/={.*=>/.test(line)) {
        issues.push({
          file,
          issue: 'Inline function in JSX (causes re-render)',
          line: idx + 1,
        })
      }

      // Find missing dependencies in useEffect
      if (line.includes('useEffect')) {
        const nextLines = lines.slice(idx, idx + 10).join('\n')
        if (!/\[.*\]/.test(nextLines)) {
          issues.push({
            file,
            issue: 'useEffect without dependency array',
            line: idx + 1,
          })
        }
      }

      // Find missing React.memo
      if (/export (const|function) [A-Z]/.test(line)) {
        const hasProps = content.includes('Props')
        const hasMemo = content.includes('React.memo') || content.includes('memo(')

        if (hasProps && !hasMemo && content.split('\n').length > 50) {
          issues.push({
            file,
            issue: 'Large component without React.memo',
            line: idx + 1,
          })
        }
      }
    })
  }

  return issues
}

Bundle Analysis Report

// generate-bundle-report.ts
import { exec } from 'child_process'
import { promisify } from 'util'

const execAsync = promisify(exec)

async function analyzeBundleSize() {
  // Build project
  await execAsync('npm run build')

  // Analyze with source-map-explorer
  const { stdout } = await execAsync(
    'npx source-map-explorer dist/**/*.js --json'
  )

  const analysis = JSON.parse(stdout)

  // Find largest dependencies
  const dependencies = Object.entries(analysis.files)
    .map(([name, size]) => ({ name, size: size as number }))
    .sort((a, b) => b.size - a.size)
    .slice(0, 20)

  console.table(dependencies)

  // Generate recommendations
  const recommendations = []
  for (const dep of dependencies) {
    if (dep.size > 100000) {
      recommendations.push({
        dependency: dep.name,
        size: (dep.size / 1024).toFixed(2) + ' KB',
        suggestion: 'Consider code splitting or finding lighter alternative',
      })
    }
  }

  return { dependencies, recommendations }
}

Analysis Reports

Comprehensive Health Report

// health-report.ts
import { exec } from 'child_process'
import { promisify } from 'util'
import { readFileSync } from 'fs'
import { glob } from 'glob'

const execAsync = promisify(exec)

interface HealthReport {
  overview: {
    totalFiles: number
    totalLines: number
    components: number
    tests: number
    coverage: number
  }
  quality: {
    typeErrors: number
    lintErrors: number
    complexity: number
    duplication: number
  }
  dependencies: {
    total: number
    outdated: number
    vulnerable: number
    unused: number
  }
  performance: {
    bundleSize: number
    renderIssues: number
    memoryLeaks: number
  }
  recommendations: Array<{
    category: string
    priority: 'high' | 'medium' | 'low'
    issue: string
    solution: string
  }>
}

async function generateHealthReport(): Promise<HealthReport> {
  // Count files and lines
  const files = glob.sync('src/**/*.{ts,tsx,js,jsx}')
  const totalFiles = files.length
  const totalLines = files.reduce((acc, file) => {
    return acc + readFileSync(file, 'utf-8').split('\n').length
  }, 0)

  // Count components and tests
  const components = glob.sync('src/**/*.{tsx,jsx}').filter(
    f => !f.includes('.test.') && !f.includes('.spec.')
  ).length
  const tests = glob.sync('src/**/*.{test,spec}.{ts,tsx,js,jsx}').length

  // Get test coverage
  const { stdout: coverageOutput } = await execAsync('npm test -- --coverage --silent')
  const coverageMatch = coverageOutput.match(/All files\s+\|\s+(\d+\.?\d*)/)
  const coverage = coverageMatch ? parseFloat(coverageMatch[1]) : 0

  // Type check
  const { stdout: tscOutput } = await execAsync('npx tsc --noEmit || true')
  const typeErrors = (tscOutput.match(/error TS\d+:/g) || []).length

  // Lint check
  const { stdout: eslintOutput } = await execAsync('npx eslint src/ --format json || true')
  const eslintResults = JSON.parse(eslintOutput || '[]')
  const lintErrors = eslintResults.reduce(
    (acc: number, r: any) => acc + r.errorCount,
    0
  )

  // Dependency audit
  const { stdout: auditOutput } = await execAsync('npm audit --json || true')
  const audit = JSON.parse(auditOutput || '{}')
  const vulnerable = audit.metadata?.vulnerabilities?.total || 0

  // Outdated packages
  const { stdout: outdatedOutput } = await execAsync('npm outdated --json || true')
  const outdated = Object.keys(JSON.parse(outdatedOutput || '{}')).length

  // Unused dependencies
  const { stdout: depcheckOutput } = await execAsync('npx depcheck --json')
  const depcheck = JSON.parse(depcheckOutput || '{}')
  const unused = depcheck.dependencies?.length || 0

  // Bundle size
  await execAsync('npm run build')
  const { stdout: sizeOutput } = await execAsync('du -sk dist')
  const bundleSize = parseInt(sizeOutput.split('\t')[0])

  // Generate recommendations
  const recommendations = []

  if (coverage < 80) {
    recommendations.push({
      category: 'Testing',
      priority: 'high' as const,
      issue: `Test coverage is ${coverage}% (target: 80%+)`,
      solution: 'Add unit tests for untested components and utilities',
    })
  }

  if (typeErrors > 0) {
    recommendations.push({
      category: 'Type Safety',
      priority: 'high' as const,
      issue: `${typeErrors} TypeScript errors found`,
      solution: 'Fix TypeScript errors to ensure type safety',
    })
  }

  if (vulnerable > 0) {
    recommendations.push({
      category: 'Security',
      priority: 'high' as const,
      issue: `${vulnerable} security vulnerabilities found`,
      solution: 'Run npm audit fix and update vulnerable dependencies',
    })
  }

  if (unused > 0) {
    recommendations.push({
      category: 'Dependencies',
      priority: 'medium' as const,
      issue: `${unused} unused dependencies`,
      solution: 'Remove unused dependencies to reduce bundle size',
    })
  }

  if (bundleSize > 500) {
    recommendations.push({
      category: 'Performance',
      priority: 'medium' as const,
      issue: `Bundle size is ${bundleSize}KB (target: <500KB)`,
      solution: 'Implement code splitting and tree-shaking optimizations',
    })
  }

  return {
    overview: {
      totalFiles,
      totalLines,
      components,
      tests,
      coverage,
    },
    quality: {
      typeErrors,
      lintErrors,
      complexity: 0, // Would need complexity analysis
      duplication: 0, // Would need duplication analysis
    },
    dependencies: {
      total: Object.keys(
        JSON.parse(readFileSync('package.json', 'utf-8')).dependencies || {}
      ).length,
      outdated,
      vulnerable,
      unused,
    },
    performance: {
      bundleSize,
      renderIssues: 0, // Would need render analysis
      memoryLeaks: 0, // Would need profiling
    },
    recommendations,
  }
}

// Generate and display report
generateHealthReport().then(report => {
  console.log('\n📊 CODEBASE HEALTH REPORT\n')
  console.log('Overview:')
  console.table(report.overview)
  console.log('\nQuality:')
  console.table(report.quality)
  console.log('\nDependencies:')
  console.table(report.dependencies)
  console.log('\nPerformance:')
  console.table(report.performance)
  console.log('\n💡 Recommendations:')
  console.table(report.recommendations)
})

Best Practices for Analysis

1. Regular Analysis

• Run analysis weekly or per sprint
• Integrate into CI/CD pipeline
• Track metrics over time
• Set quality gates

2. Prioritize Findings

• High: Security, critical bugs, major performance issues
• Medium: Code quality, maintainability, moderate optimizations
• Low: Style issues, minor refactoring, nice-to-haves

3. Actionable Recommendations

• Provide specific solutions
• Include code examples
• Estimate effort required
• Link to documentation

4. Continuous Improvement

• Track progress on metrics
• Celebrate improvements
• Learn from regressions
• Update standards

Tools & Commands

Static Analysis

# TypeScript type checking
npx tsc --noEmit

# ESLint
npx eslint src/ --ext .ts,.tsx

# Complexity analysis
npx complexity-report src/

# Code duplication
npx jscpd src/

Dependency Analysis

# Security audit
npm audit
npx snyk test

# Unused dependencies
npx depcheck

# Outdated packages
npm outdated
npx npm-check-updates

# License check
npx license-checker

Performance Analysis

# Bundle analysis
npx webpack-bundle-analyzer dist/stats.json

# Source map explorer
npx source-map-explorer dist/**/*.js

# Performance profiling
npm run build -- --profile

Code Quality

# Coverage
npm test -- --coverage

# Mutation testing
npx stryker run

# Code quality metrics
npx plato -r -d report src/

Anti-Patterns to Detect

React Anti-Patterns

1. Prop Drilling: Passing props through many levels
2. God Components: Components doing too much
3. Inline Functions: Creating new functions on every render
4. Missing Keys: Lists without proper key props
5. Index as Key: Using array index as key
6. Direct State Mutation: Mutating state directly
7. Missing Dependencies: useEffect without proper deps
8. Unnecessary Re-renders: Components re-rendering too often

General Anti-Patterns

1. Magic Numbers: Hard-coded values without explanation
2. Copy-Paste Code: Duplicated code blocks
3. Long Functions: Functions over 50 lines
4. Deep Nesting: More than 4 levels of nesting
5. Too Many Parameters: Functions with 5+ parameters
6. God Objects: Classes/objects doing everything
7. Tight Coupling: High dependencies between modules
8. Missing Error Handling: No try-catch or error boundaries

When to Use This Skill

Activate this skill when you need to:

• Analyze codebase quality
• Find performance bottlenecks
• Detect code duplication
• Audit dependencies
• Review architectural patterns
• Identify technical debt
• Assess code complexity
• Find security vulnerabilities
• Optimize bundle size
• Review code before release
• Onboard to new codebase
• Prepare for refactoring

Output Format

When analyzing codebases, provide:

1. Executive Summary: Key findings and metrics
2. Detailed Analysis: In-depth findings by category
3. Metrics Dashboard: Visual representation of health
4. Recommendations: Prioritized action items
5. Code Examples: Before/after refactoring suggestions
6. Implementation Plan: Steps to address issues

Always provide actionable, specific recommendations with clear priorities and estimated effort.